The over-all objectives of this proposal are to document any changes in glycolytic and phosphate metabolism in the fetal rat heart that may occur consequent to in utero exposure to estrogenic and progestogenic hormones to obtain definitive metabolic information in relation to the chemical reports that in utero exposure to the estrogenic and progestogenic hormones which are commonly used in the USA as oral contraceptives may be associated with the development of congenital heart defects in the human infant. The long term goal of this proposal is to obtain information which will assist in understanding of some of the metabolic factors which may be involved in the pathogenesis of congenital heart defects. Pregnant rat females will be given estrogenic and progestogenic hormones. Fetuses will be examined at various times to determine the anatomic stage of development. At the same times specimens of the developing heart will be chemically analyzed for approximately 20 phosphorylated intermediates by an automatic process developed in this laboratory applicable to total specimens of one milligram of tissue. The radioactive phosphorous turnover through these intermediates will be measured in some cases. A comparison of the concentrations of the various phosphate intermediates will be made between the control fetuses from the same dam and those subject to exposure to the steroid materials.